Cisco 400-007 Exam With Confidence Using Practice Dumps

B (East-West API between controllers):In multicontroller SDN architectures, East-West APIs allow controllers to synchronize state, policies, and tasks, enabling distributed control while presenting a unified control plane view. This ensures that tasks can be performed on any controller consistently.

Other options explained:

A: Root controllers are not standard in modern SDN distributed architectures.

C: Physical connectivity alone doesn ' t synchronize state or tasks.

D: OpenFlow governs switch forwarding, not controller-to-controller interaction.

Virtual Private LAN Service (VPLS) provides Layer 2 VPN connectivity over MPLS. Each Provider Edge (PE) device must learn and maintain MAC addresses per virtual instance.

PE Scalability is the primary concern: With 2000 VLANs, each PE participating in those instances must maintain a large forwarding table and handle associated control-plane activity.

MAC learning and aging, along with full-mesh label-switched paths (LSPs), place a heavy burden on CPU and memory.

Flooding (A) is expected but not the primary concern; it’s a symptom of scale.

The underlying transport (C) and VLAN ID limits (D) are important but not as critical in the context of PE resource scalability.

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